WIRELESS SENSOR NETWORK PERFORMANCE IN HIGH …

WIRELESS SENSOR NETWORK PERFORMANCE IN

HIGH VOLTAGE AND HARSH INDUSTRIAL

ENVIRONMENTS

INAM-UL-HAQ MINHAS

This thesis is presented as part of Degree of

Master of Science in Electrical Engineering

Blekinge Institute of Technology July 2010

Blekinge Institute of Technology

School of Engineering

Department of Signal Processing

Supervisor: Professor Wlodek Kulesza

Industrial Supervisor: Jonas Neander

Examiner: Professor Wlodek Kulesza

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Abstract

The applications of wireless sensor networks, WSN, are getting popular in the different areas

reaching from daily usage to industrial usage. The performance evaluation of WSN deployed in

industrial and high-voltage areas is receiving a great attention and becoming an interesting area

of research.

This thesis addresses the performance issues of WSN in high-voltage and harsh industrial

environments. This study has been carried out at the facilities of High-Voltage Test Lab of

ABB.

Typically, wireless sensor network contains wireless field devices (nodes) connected to a base

station via a central gateway. The gate way centralizes information gathered and processed by

the nodes. The nodes can communicate with each other and with the gateway via radio wave.

The quality and usability of the data sent by WSN can be degraded due to the packet loss and

delay. In the presence of high-voltage, the electromagnetic interference, EMI, can affect the

performance of WSN.

In this study the performance of WSN is evaluated in terms of packet loss and delay. We also

focus on the effect of EMI on hardware devices as well as on signal transmission. EMI was

expected at wide frequency band due to harsh industrial and high voltage environments. It was

expected that EMIs could increase a bit error rate and/or packet loss. The EMI can also change

the sensitivity of the nodes.

For the performance evaluation of WSN network throughput, latency, path stability, data

reliability and average value of the received signal strength indicator, RSSI, are used and

measured. The results show that the electromagnetic frequencies of harsh industrial and high

voltage environments affect the wireless sensor network performance.

Keywords: WSN, EMI, Latency, Path Stability, Data Reliability, RSSI.

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Acknowledgements

All praises and thanks to Almighty ALLAH, the most beneficent and the most Merciful.

I would like to thank my supervisor Wlodek Kulesza from Blekinge Institute of Technology, Jonas

Neander from ABB Västerås for their support and kind advices during my work. I would like to

thank all ABB CRC Västerås crew.

I would like to acknowledge all who played a role in my project either directly or indirectly.

Specially thanks to my brother Minhas Tahir Nawaz and my Parents.

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TABLE OF CONTENTS

1 INTRODUCTION ..................................................................................................................................................10

1.1 USED TERMINOLOGY .............................................................................................................................................. 10

1.2 THESIS STRUCTURE ................................................................................................................................................. 11

2 REVIEW OF RELATED WORKS .............................................................................................................................12

3 PROBLEM STATEMENT .......................................................................................................................................14

4 THEORETICAL BACKGROUND—OVER VIEW OF USED TECHNOLOGY...................................................................15

4.1 WIRELESS HART TECHNOLOGY ................................................................................................................................ 16

5 TESTS SCENARIOS AND SET UPS ........................................................................................................................17

5.1 TEST SCENARIOS .................................................................................................................................................... 18

5.1.1 Non-Industrial Environment Tests ............................................................................................................. 18

5.1.2 Industrial Machine Lab Environment Tests ............................................................................................... 19

5.1.3 DC High Voltage Environment Tests......................................................................................................... 20

5.1.4 AC High Voltage Environment Tests - High Voltage Transformer ............................................................. 23

5.1.5 EMI Test in High Voltage and Machine Lab .............................................................................................. 25

6 TEST RESULTS AND ANALYSIS .............................................................................................................................26

6.1 NETWORK STATISTICS ............................................................................................................................................. 26

6.1.1 Analysis of Non Industrial Environments Test Results............................................................................... 26

6.1.2 Analysis of Industrial Machine Lab Test Results ....................................................................................... 28

6.1.3 Analysis of DC High Voltage Environment Tests Results ........................................................................... 29

6.1.4 Analysis of AC High Voltage Environment Tests Results ........................................................................... 33

6.2 PATH STATISTICS .................................................................................................................................................... 35

6.2.1 Analysis of Non-Industrial Environment Test Results ................................................................................ 35

6.2.2 Analysis Industrial Machines Lab environment Test Results ..................................................................... 36

6.2.3 Analysis DC High Voltage Environment Test Result .................................................................................. 37

6.2.4 Analysis of AC High Voltage Environment Test Results ............................................................................. 38

6.3 AVERAGE RSSI VALUE FOR TRANSMISSION.................................................................................................................. 39

6.4 ANALYSIS OF EMI TEST RESULTS ............................................................................................................................... 42

6.4.1 Spectral Measurements for EMI in 2.4 GHz band Frequency .................................................................... 42

6.4.2 Measurements of EMI in 2.4 GHz Frequency Spectrum in DC High Voltage ............................................. 44

6.5 RESULT ANALYSIS FOR COMPLETE TEST ...................................................................................................................... 45

6.5.1 Non Industrial Environments Test ............................................................................................................. 45

6.5.2 Industrial Machines Lab Environment Test ............................................................................................... 45

6.5.3 AC High Voltage Environment Test ........................................................................................................... 45

6.5.4 All Test Result Summary ............................................................................................................................ 46

7 CONCLUSIONS AND FUTURE WORK ...................................................................................................................47

8 REFERENCES .......................................................................................................................................................48

9 APPENDIX ..........................................................................................................................................................50

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LIST OF FIGURE

FIGURE 1: SMARTMESH MOTE AND NETWORK MANAGER ............................................................................................. 17

FIGURE 2: NETWORK TOPOLOGY FOR NON INDUSTRIAL TEST ........................................................................................ 18

FIGURE 3: ABB LAB WITH TWO MOTOR MACHINES ......................................................................................................... 19

FIGURE 4: MACHINE LAB NETWORK TOPOLOGY .............................................................................................................. 20

FIGURE 5: DC HIGH VOLTAGE TEST SETUP ....................................................................................................................... 21

FIGURE 6: THE BLOCK DIAGRAM FOR DC HIGH VOLTAGE TEST CIRCUIT .......................................................................... 22

FIGURE 7: THE BLOCK DIAGRAM FOR TRANSFORMER AND METALLIC CAGE .................................................................. 22

FIGURE 8: THE VOLTAGE TEST ALONG TIME FOR HIGH VOLTAGE DC TEST ...................................................................... 23

FIGURE 9: BLOCK DIAGRAM OF AC HIGH VOLTAGE TEST SETUP ..................................................................................... 23

FIGURE 10: AC HIGH VOLTAGE TEST SETUP ...................................................................................................................... 24

FIGURE 11: THE CIRCUITRY OF AC HIGH VOLTAGE TEST SETUP ....................................................................................... 24

FIGURE 12: AC VOLTAGE WITH RESPECT TO TIME ........................................................................................................... 25

FIGURE 13: STABILITY AND LATENCY GRAPH OF NONINDUSTRIAL ENVIRONMENT TEST ................................................ 26

FIGURE 14: DATA PACKET TRANSMITTED AND FAILED PER TIME SLOT FOR NONINDUSTRIAL ENVIRONMENTS TEST ... 27

FIGURE 15: STABILITY AND LATENCY GRAPH OF INDUSTRIAL MACHINE LAB TEST .......................................................... 28

FIGURE 16: DATA PACKET TRANSMITTED AND FAILED PER TIME SLOT FOR MACHINE LAB TEST ................................... 29

FIGURE 17: STABILITY AND LATENCY GRAPH OF DC HIGH VOLTAGE TEST ....................................................................... 30

FIGURE 18: DATA PACKET TRANSMITTED AND FAILED PER TIME SLOT FOR DC HIGH VOLTAGE TEST ............................ 31

FIGURE 19: THE VOLTAGE VS. STABILITY AND RELIABILITY .............................................................................................. 32

FIGURE 20: STABILITY AND LATENCY GRAPH OF AC HIGH VOLTAGE TEST ....................................................................... 33

FIGURE 21: DATA PACKET TRANSMITTED AND FAILED PER TIME SLOT FOR AC HIGH VOLTAGE TEST ............................ 34

FIGURE 22: PATH STABILITY FOR MODE TO AP IN NONINDUSTRIAL ENVIRONMENT ...................................................... 35

FIGURE 23: PATH STABILITY FOR A MODE TO AP IN MACHINE LAB TEST ........................................................................ 36

FIGURE 24: PATH STABILITY FOR A MODE TO AP IN DC HIGH VOLTAGE TEST ................................................................. 37

FIGURE 25: PATH STABILITY FOR A MODE TO AP IN AC HIGH VOLTAGE TEST ................................................................. 38

FIGURE 26: AVERAGE VALUE OF OUTPUT POWER PER TIME SLOT FOR TRANSMISSION IN NON INDUSTRIAL TEST ....... 39

FIGURE 27: AVERAGE VALUE OF OUTPUT POWER FOR TRANSMISSION IN MACHINE LAB TEST ..................................... 40

FIGURE 28: AVERAGE VALUE OF OUTPUT POWER FOR TRANSMISSION IN DC HIGH VOLTAGE TEST .............................. 41

FIGURE 29: AVERAGE VALUE OF OUTPUT POWER FOR TRANSMISSION IN AC HIGH VOLTAGE TEST .............................. 41

FIGURE 30: THE 2.4 GHZ SPECTRUM WHEN MACHINES WERE IN OFF STATE .................................................................. 42

FIGURE 31: 2.4 GHZ SPECTRUM WHEN MACHINES ARE OPERATING .............................................................................. 43

FIGURE 32: 2.4 GHZ SPECTRUM DC HIGH VOLTAGES TEST .............................................................................................. 44

8

LIST OF TABLE

TABLE 1. COMPARISON OF WIRELESS HART AND ZIGBEE .................................................................................. 15

TABLE 2. OSI LAYER MODEL AND WIRELESS HART STACK ................................................................................ 16

TABLE 3. COMPARISON OF STABILITY AND LATENCY - OFF .............................................................................. 46

TABLE 4. COMPARISON OF STABILITY AND LATENCY- ON................................................................................. 46

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LIST OF ABBREVIATIONS

ACK Acknowledgment

CSMA Carries Sense Multiple Access

DSN Distributed Sensor Networks

DSSS Direct Sequence Spread Spectrum

EMC Electromagnetic compatibility

EMI Electromagnetic Interference

FHSS Frequency Hopping Spread Spectrum

ISM Industrial, Scientific and Medical

IEMI Intentional Electrometric Interference

MAC Medium Access Control

MIC Message Integrity Code

PHY Physical layer

RSSI Received Signal Strength Indicator

TDMA Time division multiple access

WSN Wireless Sensor Network

PkRx Total number of packets received by network motes.

PkTx Total number of packets transmitted by network motes

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1 INTRODUCTION

A wireless sensor network (WSN), consists of wireless field devices called nodes and a central

base station. These sensor nodes communicate wirelessly with each other and also with the base

station, within their radio communication range. A sensor node is made up of a microprocessor, a

small amount of memory, a radio transceiver and one or more sensors.

History of sensor networks shows the military application as the beginning of this technology.

Distributed Sensor Networks (DSN) project from Defense Advanced Research Projects Agency

(DARPA) of the USA during 80’s is one of the first known steps for modern sensor networks.

WSN has been lately used and developed not only in the military field, but also in civilian,

commercial, medical and industrial application areas. In today’s life WSNs are used in

monitoring high-security areas, environmental sensing, industrial applications like heating

monitoring, home automation or medical application like checking vital signs, patient tracking,

etc.

WSN, Bluetooth, wireless local area network (WLAN), radio-frequency identification (RFID)’s

and others technologies operate in 2.4 GHz band which make it overloaded. The 2.4 GHz band is

licensed free and available worldwide and has high band width. Due to this, a trend to using 2.4

GHz band is increasing rapidly. For reliable communication within the band, the primary

requirement is a minimum interference between devices utilizing this band [5].

However the WSN operations in industrial environment can be also interfered by power grids and

heavy machines. The industrial environment characterized by high voltage, high electric and

magnetic fields, can cause strong electromagnetic interferences.

The main purpose of this thesis is to investigate the performance of WSN in high voltage and

harsh industrial environments. High EMIs were expected at different frequency bands in this kind

of environments. These EMIs could increase a bit error rate and/or packet loss. In this thesis we

thoroughly investigate the impact of EMI on WSN hardware devices and on the radio

transmission. The thesis reports results of practical tests which are done by deploying wireless

network devices in realistic industrial environments of ABB.

In our experiments the wireless HART technology and DUST Network technology products are

used to investigate performance of WSN in high voltage and harsh industrial environments.

1.1 Used Terminology

In order to study and analyse the performance of a certain given WSN, we can list three key

performance parameter; such as reliability, stability and latency. For detail comparison and study

of overall network, we consider s: network statistics, path statistics and node statistic, specifically

defined as:

• Network Statistics: Each performance parameter is based on overall WSN within a given time

interval.

• Path Statistics: Each performance parameter is based only for single path between any two

nodes.

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• Node statistics: The node statistics concerns performance of the node individually.

• Data Reliability of the network is percentage of expected data packets that the base station

actually received [3]. So a high reliability ensures that no sensed data has been lost during the

communication process.

(1)

Where PkRx and PkTx are total numbers of packets received and transmitted respectively by

the network node.

• Network / Path Stability of the network is percentage of data packets transmit successfully [3].

(2)

• Latency is the average time it takes for each data packet from the generating sensor node to the

base station [3]. The network manager at base station calculates data latency for each packet

by subtracting the time the packet was received at manager from the packet timestamp, which

is defined as the packet was generated by the mote [6], here mote is defined as a sensing node

which is monitored by the manager.

• Fail is a measure of number of packets for which no acknowledgement was received.

1.2 Thesis Structure

The remainder of this thesis is, section 2, describes the EMI endurance and coexistence in ISM

2.4 GHz band. The effect of electromagnetic interference on wireless sensor network and related

work has been described. Whereas, section 3, contains problem statement, research questions,

hypotheses and main contribution of this thesis work. In section 4, an overview of wireless sensor

networks and the most wide-spread wireless sensor network protocols are given, with special

focus on the Wireless HART technology, which represents the central issue for the thesis work.

Section 5, which investigates the functionality of wireless radio communication in a high-voltage

environment, typically related to industrial processes, transformation stations and other parts of

the power distribution grid. Section 6 is the last section, which verifies the functionality of

wireless radio communication in high voltage and industrial environments.

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2 REVIEW OF RELATED WORKS

Sensor network is one of the most rapidly expanding research areas within information

technology. Today we find potential applications for sensor network technology almost

everywhere in our everyday life, for example within sports, medicine, process industry,

agriculture, energy generation etc. We can surely say that sensor networks would become a part

of society critical systems in near future. Due to increasing demand of WSN technology in

different areas, a lot of efforts have been done to improve the performance, to make technology

faster more accurate and reliable.

Different studies have been conducted to evaluate the performance of WSN. In [20] authors

investigated the packet loss probability of a link in a sensor network and found that it cannot be

predicted accurately using the distance between the nodes. The authors in [22] have studied the

packet loss behaviour in a wireless broadcast sensor network and observe that different receivers

are likely to experience simultaneous losses. In [23], the authors evaluated the performance of

wireless personal network using data throughput, delivery ratio, and received signal strength

indication (RSSI) as the performance metrics. Similarly in [24], the authors evaluated the

performance of WSN in indoor scenarios; particularly they consider the behavior of RSSI and

characterized the performance of WSN in term of end-to-delay and throughput.

The reliability and robustness of WSN communications are affected by the possible radio

interference like Bluetooth, WLAN, IEEE 802.15.4 [19] etc. Most of the industrial WSN devices

share the 2.4 GHz ISM band [21]. While exploring interference, researchers have focused on the

specific protocols, e.g., IEEE 802.11b (WLAN), Bluetooth, and ZigBee [9].

Usually radio interference in WSN causes a serious threat in reliable communication. There are

currently several developing technologies with interesting features considering the mitigation of

EMI for sensor networks. Encapsulated materials are feasible and are of more interest. Laminate

materials like Proof Cap [14] will give both protection for EMI and enables the integration of

communication antennas.

The threat of EMI is controlled by adopting the practices of electromagnetic compatibility

(EMC), which has two complementary aspects: it describes the capacity of electrical and

electronic systems to operate without interfering with other systems and also describes the ability

of such systems to operate as intended within a specified electromagnetic environment [21].

Interference can propagate from a “source” to a “victim” by the main distribution network to

which both are connected. This is not well characterized at high frequencies for example

connected electrical loads can present virtually any RF impedance at their point of connection

[11].

The external interference from a system whose purpose is not data communication might be the

effect of industrial environments, grid stations or the environment with strong electric and

magnetic fields. This external interference is also known as electrical interference.

Most existing studies are based either on over-simplistic environmental models assuming

Gaussian background noise, or on the assumption that interference arises from peer [27]. There

are two types of disturbance which have received a considerable attention in research under the

umbrellas of channel modeling and MAC protocol design, respectively. The third type of

disturbance is due to external interference possibly even from a system whose purpose is not data

communication has been not much overlooked interference [27].

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Electrical machinery and lighting systems are main sources of electrical interference [25, 26]. In

most cases, the interference results from sparking, arcing and electrical discharges. In a few

instances, the interference is caused by electrical control devices such as motor speed controls,

temperature controllers and lighting dimmers. High-voltage equipment, especially neon signs, is

also a known source of interference [25, 26].

The high voltages in neon systems can also cause leakage discharges, known as corona, which

create electrical noise [28]. Other devices that use high voltages are also prone to corona and can

cause wireless interference. The discharge in the neon tubes themselves generates surprisingly a

little interference under normal circumstances. However, if the tubes are dimmed by lowering the

applied voltage, there is a point where they will generate huge amounts of radio interference [25].

In this thesis, we analyze the performance of wireless senor network in the laboratory scenarios at

ABB, test scenarios include Machine lab environment, DC high-voltage and AC high-voltage

labs environment. Moreover we perform the experiments in the office environment to compare

the results. Likewise the [9, 23, 24], we use the throughput, delay, and RSSI as performance

indicator to compare the performance of WSN. Furthermore path stability and data reliability was

also considered. Contrary to [9, 23, 24] we uses the wireless standard HART [10], which is

simple and TDMA-based wireless mesh networking technology. In [8] authors compare the

ZigBee and HART wireless technology for industrial use and found that HART is most suitable

for this purpose.

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3 PROBLEM STATEMENT

In high voltage and harsh industrial environments, electromagnetic interferences are expected at

different frequency bands. These EMIs could increase a bit error rate and data packet loss in

wireless communication. In such environment expected EMIs can also affect the WSN device’s

sensitivity, which causes the packet loss and delay in response time. Our research questions are:

• How the high voltage and harsh industrial environments do affect the WSN performance?

• Do the EM frequencies produced due to high voltage and industrial environments,

interfere in WSN communication?

We assumed that the WSN performance is degraded due to the presence of high voltage and

industrial environments. External EM interferences cause time delay and transmission loss.

The main contributions of the thesis can thus be summarized:

• Comparative study of WSN technology.

• Set up the radio tests for WSN performance.

• Design the EMI tests for monitoring the EM frequencies in high voltage and industrial

environments.

• Capture and collect the WSN data analyzed with the help of Matlab.

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4 THEORETICAL BACKGROUND—OVER VIEW OF USED TECHNOLOGY

There are two principal standards for WSN technologies which are realistic choices for a real

usage of a WSN: Wireless HART and ZigBee.

ZigBee [10] is a set of high-level communication protocols based on the IEEE 802.15.4-2003

standard, suited for low data rate WPANs. It aims to provide a simpler and less expensive

specification than other WPANs. ZigBee operates in the industrial, medical and scientific radio

bands. Typical application areas include home entertainment and control, mobile services,

commercial building. The standard specifies the physical, MAC and data link protocol layers.

Concerning the physical layer, ZigBee uses direct-sequence spread spectrum (DSSS) like some

standards of the IEEE 802.11 family. ZigBee has been developed to add mesh networking to the

IEEE 802.15.4-2003. It is particularly suited for embedded systems where reliability and

versatility are more important than the bandwidth [13].

The HART Communication foundation (HCF) released the new HART 7 specification on

September 2007. HART is a master/slave protocol which means that a field (slave) device only

acts when called by a master. The HART protocol can be used in various modes for

communicating information to/from smart field instruments and central control or monitoring

systems. The HART 7 specification includes Wireless HART [12], the first open wireless

communication standard designed specifically for industrial environments in which plant

applications need reliable, secure and simple wireless communication.

For industrial application of WSN the most important argument which makes Wireless HART as

our preferred choice for this thesis is that in ZigBee there is no frequency diversity since the

entire network shares the same static channel, making it highly susceptible to both unintended

and intended jamming. The lack of path diversity means that in a case when a link is broken, a

new path from destination has to be set up. Others less significant comparisons like battery life

time, etc. are shown in Table 1.

Table 1. Comparison of wireless HART and ZigBee

Features Wireless HART ZigBee Mesh Architecture Full Mesh Hybrid Star Mesh

Self-forming, self-healing

network

Yes Central network

coordinator

Battery Years Years

Deterministic power

management

Yes No

Reliability and stability in

harsh

environment

High Low

Channel hopping Yes No

Multiple access scheme Time Synchronized CSMA

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4.1 Wireless HART Technology

The key feature of Wireless HART is the combination of direct sequence spread spectrum

(DSSS) and frequency hopping spread spectrum (FHSS) which are frequency hopping

mechanism that can effectively suppress the sudden interference [2].In wireless HART another

technical feature is the combination of Carrier Sense Multiple Access (CSMA) and Dynamic

Time Division Multiple Access (TDMA) which gives advantages of TDMA and CSMA [2]. The

network layer uses the intelligent mesh network technology. Due to interference when path is

interrupted, the device switches on other communication path of good quality [2]. The transport

layer uses connection oriented data transmission technology by end to end retransmission

mechanism to ensure the high reliability of data transmission [2]. The wireless hart protocol uses

the intelligent network management.

The other technical features of Wireless HART are:

• Highly reliable self-organizing network,

• Using TDMA to avoid message conflicts,

• Adaptive frequency hopping mechanism ,

• Automatic request retransmission which ensures the success rate of packet

transmission,

• Mesh routing to improve the reliability of end to end communication,

• High degree of reliability,

• Use of multiple channels within the band,

• Very high resistance to active interferers,

• Higher resistance to passive interferers like multipath,

• Simultaneous use of more than one channel increases throughput.

The Wireless HART protocol is loosely organized around the OSI-7 layered architecture. The

protocol defines 5 separate layers - the Physical Layer, the Data-link Layer, the Network Layer,

the Transport Layer and the Application Layer. Table 2 shows the Wireless HART layered

architecture.

The Wireless HART Networks must be managed and connected to the real world. As a central

component, the Wireless HART Gateway provides all these functionalities [2].

Table 2. OSI Layer Model and Wireless HART Stack

OSI-7 Layer Model Wireless HART Stack

Application Layer Command oriented, predefined data types and applications

Presentation Layer Not used

Session Layer Not used

Transport layer Reliable stream transport, negotiated segment sizes, transfer of

large data sets

Network Layer Power optimized, redundant path, self-healing, wireless mesh

network

Data link Layer Secure and reliable, Time Synched TDMA/CSMA, Frequency

Agile with ARQ

Physical Layer 2.4 GHz wireless, 802.15.4 based radios, 10 dBm Tx power

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5 TESTS SCENARIOS AND SETUPS

In this chapter we present the test scenario and results for deploying wireless sensor notes in real

high voltage and industrial machine environments.

At the start we perform experiments in normal office environments during night time to reduce

the chances of interference from wireless communication sources. We use these results as

reference for office environments and we compare these results with all other scenarios i.e.

deploying the wireless sensor network in high voltage and industrial environments.

The WSN uses DUST SmartMesh network technology. Dust SmartMesh technology is based on

Wireless HART, the technical features of used technology are explained in chapter 4. SmartMesh

network has one manager and can have up to 250 nodes [3]. SmartMesh networks are reliable,

ultra low power.

The used DUST SmartMesh products are

• The SmartMesh IA-510 D2510 Network Manager,

• The SmartMesh Motes.

Figure 1: SmartMesh Mote and Network Manager

The SmartMesh network manager is responsible for network configuration, management, and

gateway functionality for field devices or nodes. SmartMesh network managers allow

programmatic access to network control commands, by using host interface application via XML

API and Serial API. In other words, the SmartMesh Mote is more intelligent than a network node.

The SmartMesh M2510 motes are ultra low-power wireless transceivers and onboard radio to

send packets [3]. (For specification of products see Appendix).

For monitoring and measurement DUST’s SmartMesh Console Software and DUST’s

SmartMesh API and Command Line Interface are used. For measurement of interference FSH

view software and FSH 6, a remote spectrum analyzer is used [6]. The collected data are analyzed

using Matlab.

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5.1 Test Scenarios

To observe the WSN performance in high voltage and harsh industrial environments we used

ABB labs. As a reference we perform the same experiments in nonindustrial environments to

observe the radio performs without the disturbances.

In order to observe the effect of high voltage and industrial environments on wireless sensor

network communication we divide our experimenters in five scenarios.

5.1.1 Non-Industrial Environment Tests

In 1st scenario, we perform test in office environments called non industrial tests and being a

reference for other tests. In this scenario we deploy wireless senor network in office environments

at night time and collect data using wireless hart technology and dust network instruments. The

efforts are taken to achieve maximum stability and minimum legacy. There is one issue needed to

consider during experiments: the behavior of network manger up time defined as the time when

nodes start stable communication or build stable network.

Non-industrial environment does not mean that the environment is completely free from

interferences. Some known external interference like WLAN, Wireless devices, RFID’s is

working in the environment. We cannot ignore these external interferences.

The tests were performed at ABB AB Corporate Research, in the office environment. The tests

were repeated for several times to make the readings reliable. We used five wireless field devices

for this test in which “node 1” was working as gateway. The distance of field devices was not

more than seven meters from access point.

Figure 2: Network topology for non industrial test

Figure 2 shows the network topology of the wireless sensor network deployed in office

environment. Where “AP” is access point or gateway and M12, M13, M19, M20 are wireless

nodes and small m depicts the distance in meter between nodes and between nodes and a

gateway.

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5.1.2 Industrial Machine Lab Environment Tests

In 2nd

scenario we select the laboratory room of ABB for real industrial environments which has

two machines of 550 kW and 450 kW and some small machines shown in figure 3.The detail

topology and experiments environment is presented in following sections.

The main reason to select this environment is to observe how wireless sensor network

communication behaves in continues lower band frequencies noise and to observe if there is any

sudden emission of frequency in the range 2.4 G Hz band (which big machine produce) and

impact of such emission on wireless communication or wireless devises.

We deployed five field devices which are shown in Figure 3. Among the five wireless field

devices “node 1” is working as gateway. The distance of field devices is not more than ten meters

from access point.

The test is divided into three steps.

1- Test in the lab when machines are not running.

2- Test in the lab when machines are running.

3- Test to monitor EM frequencies in lab when machines are running.

Figure 3: ABB Lab with two motor machines

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Figure 4: Machine lab network topology

Figure 4 shows the network topology of the wireless sensor network deployed in industrial

machine lab tests, where “AP” is access point and gateway and M12, M13, M19, M20 are

wireless nodes and small m depicts distance in meter between nodes and between nodes and a

gateway. Machines 1 and 2 are machines of 550 kW, 523 A, 690 V and 450 kW, 230 A, 9300 V

respectively.

5.1.3 DC High Voltage Environment Tests

The test setup in the DC High Voltage Lab consists of a transformer to control the voltage, and a

secondary transformer to increase the voltage and then a rectifier circuit to convert AC into DC.

The high voltage environments may produce a corona, which is sparking or lightning due to

ionization in the air.

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Figure 5: DC high voltage test setup

In Figure 5 the network topology of the wireless sensor network deployed in DC High Voltage

Lab is shown along with a metallic cage in which lighting effect is produced.

AP is access point gateway and M12 and M13 are wireless nodes and small m depicts distance in

meters between nodes and between nodes and a gateway. The arrow from original setup to

topology shows were the nodes are placed in original test setup.

We used three wireless field devices in this experiment, but one of them is working as gate way

node and the remaining two are field devices which are placed on DC high voltage experimental

equipment. The distance of field devices is not more than ten meters from access point.

The test is divided into three steps.

1. WSN performance test in the DC High Voltage Lab.

2. WSN performance test when DC high voltage is increasing step by step.

3. Test to monitor EM frequencies in lab.

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Figure 6: The block diagram for DC High Voltage Test Circuit

The setup as shown in the Figure 6 consists consist of an adjustable transformer to control the

voltage, a secondary transformer to increase the voltage, a rectifier circuit made of diodes to turn

AC into DC current, a conductor of about 6 meters and a termination point which leaves a gap

between the line and the ground.

The termination, the gap (no. 1 in the diagram) and the ground are surrounded by a metallic cage

as seen in Figure 7 in order to simplify the geometry for other tests that were made at the same

time. Therefore some collateral Faraday box isolation effects can be founded. With this set-up it is

possible to measure the effects of DC current installations and corona of this type of environments

as well. Corona is a typical electrical discharge, or sparking, produced by the ionization of the air

nearby where the high voltage is present.

Figure 7: The block diagram for transformer and metallic cage

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Test voltage

0

50

100

150

200

250

300

350

400

12:00:00 14:24:00 16:48:00 19:12:00 21:36:00 00:00:00 02:24:00 04:48:00 07:12:00 09:36:00

Time

DC

Vo

lta

ge

( k

V )

"Voltage"

Figure 8: The voltage test along time for High Voltage DC Test

In the Figure 8, we can see that the test voltage was progressively modifying along the time,

later on it maintain fixed level at 300 kV.

5.1.4 AC High Voltage Environment Tests - High Voltage Transformer

This test investigates how the WSN behaves on proximity to high voltage transformers. The setup

shown in Figure 9 consists of an exciter transformer, a tunable reactor, which is a high voltage

series resonant test system of variable inductance to test resonant loads, a voltage divisor to

measure and a simple load.

Figure 9: Block Diagram of AC high voltage test setup

The test is divided into two steps.

1. WSN performance test in the lab without high voltage.

2. WSN performance test in the lab when high voltage is increasing.

24

Figure 10: AC High voltage test setup

The topology of AC high voltage test is shown in Figure 10.The same as in the previous test, we

use three wireless field devices for this test in which the first node is working as gate way and the

remaining two filed devices are placed on experimental equipment as shown in Figure 10. The

distance of field devices from access point is not more than sixteen meters.

Figure 11: The circuitry of AC high voltage test setup

25

The test took 7 hours, where the first 6 hours transformer system worked with an output load of

77 kV. The last hour the power was switched off in order to study if the laboratory environment

caused any effect on the network behavior.

0

10

20

30

40

50

60

70

80

90

09:07 10:19 11:31 12:43 13:55 15:07

Voltage (kV)

Voltage (kV)

Figure 12: AC Voltage with respect to time

5.1.5 EMI Test in High Voltage and Machine Lab

For measurement of EMI in high voltage and industrial environment we design EMI test in same

environments as mention in 5.1.2 and 5.1.3 where we investigate the WSN performance.

We divided EMI tests in following sub scenarios.

1- Measurements of EMI in 2.4 GHz Frequency Spectrum in machine lab,

2- Measurements of EMI in 2.4 GHz Frequency Spectrum in DC high voltage.

In both sub scenarios we use two test setups.

1- When WSN filed devises are transmitting,

2- When WSN filed devises are disabled.

26

6 TEST RESULTS AND ANALYSIS

In this section we analyze the tests result from the all four scenarios and finally we compare them

with each other.

6.1 Network Statistics

6.1.1 Analysis of Non Industrial Environments Test Results

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 49 5

9 6

9 7

9 8

9 9

1 0 0

% N

etw

ork

Sta

bili

ty

N e t w o rk S t a t is t i c s

1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 40

0 . 2

0 . 4

0 . 6

0 . 8

1

1 . 2

1 . 4

1 . 6

1 . 8

2

T im e " 1 5 m in u t e s E a c h In t e rva l"

Late

ncy in s

econd

Figure 13: Stability and latency graph of nonindustrial environment test

In Figure 13 the x-axis shows time t interval, and each interval is fifteen minutes. Along y-axis

the percentage network stability and latency in seconds are plotted. From Figure 13 we observe

that the network stability is above 99.00 % and latency is below 0.6 second, which is very close

to expected result in non industrial environment. During the test the data reliability of the network

is 100%, which means that the manager receives all expected data.

The average value of network stability is 99.7 % with variance 0.08 during nonindustrial

environment test.

27

1 2 3 4 5 6 7 8 9 10 11 12 131400

1425

1450

1475

1500

1525

1550

1575

1600

1625

1650

Time interval(15 min each interval)

Packet Tx

Network Statistics " Tx & Fail "

1 2 3 4 5 6 7 8 9 10 11 12 130

5

10

15

20

25

30

Time " 15 minutes Each Interval"

Fail

Figure 14: Data Packet Transmitted and Failed per time slot for nonindustrial environments test

In Figure 14 the x-axis shows time t interval, each interval is fifteen minutes. Along y-axis the

number of packets transmitted and the number of packet failed to get ACK are plotted. From

Figure 14 we can see that in each time interval the number of packets for which no

acknowledgement was received is less than 10 packets per time slot with a total average around 5

packets per time slot.

28

6.1.2 Analysis of Industrial Machine Lab Test Results

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 202095

96

97

98

99

100

% N

etw

ork

Sta

bility

Network Statistics

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20200.4

0.5

0.6

0.7

0.8

0.9

111


Late

ncy in s

econd

Figure 15: Stability and latency graph of Industrial Machine lab test


percentage network stability and latency in seconds are plotted. In Figure 15 the blue line shows

the network stability when machines were not running, and red line shows the network stability

when machines were running. The graph shows that the stability is around 99.5% when machines

are not running and when the machine are in running state, the network stability drop down with

minimum value 96.5% and an average of 97.8%. More than 2% stability decreasing shows that

the machines running environment affect the WSN performance.

The green line in latency graph from Figure 15 is the average latency of the WSN before the

machines were running with average 0.57 seconds and the red line is the latency when machines

were running, it shows an average latency of 0.68 seconds. An increase in latency shows the

WSN performance degradation in machines running environments.

The average value of network stability is 98.05 % with variance 4.205 during industrial

environment test.

29

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20201300

1310

1320

1330

1340

1350

1360

1370

1380

1390

14001400

Packet Tx

Network Statistics "Tx & Fail"

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20200

5

10

15

20

25

30

35

40

45

5050


Fail

Figure 16: Data Packet Transmitted and Failed per time slot for machine lab test


number of packets transmitted and the number of packets failed to get ACK are plotted. The

Figure 16 shows that less than 10 packets per time slot fails to get ACK when machines are not

running but when the machines are running the number of packets fails to get acknowledgement

increased up to maximum 46 packets per time slot, with an average of 30 packets per time slot.

6.1.3 Analysis of DC High Voltage Environment Tests Results

In our hypothesis we assume that high voltage environments can affect the wireless

communication and wireless devices which produce different level of electromagnetic

frequencies by increasing and decreasing voltage and current level and sparking or lighting

effects. Such high level electromagnetic frequencies can produce interference in wireless sensor

network communication band.

30

1 2 3 4 5 6 7 8 9 1095

96

97

98

99

100%

Netw

ork S

tability

Network Statistics

1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1


Latency in second

Figure 17: Stability and latency graph of DC High voltage test


percentage network stability and latency in seconds are plotted. In Figure 17a the blue line shows

the network stability of the network when voltage level from experimental setup is zero or no

voltage. Red line shows the network stability when DC high voltage is present in setup and is

increasing step by step from 0 up to 400 kV. The graph shows that the stability is around 99%

when voltage level is zero but when DC high voltage is present in experimental setup we can see

the degradation in stability drops down to 3%.

In Figure 17 the latency graph is plotted with green line which is the average latency of the WSN

when voltage level is zero, which is average 0.6 seconds. In the latency graph, the red line shows

the latency when DC high voltage is present, which is 0.77 seconds on average. An increase of

0.170 seconds in latency shows that the WSN performance decreases.

The average value of network stability is 97.2 % with variance 5.78 during nonindustrial

environment test.

31

1 2 3 4 5 6 7 8 9 10 11650

675

700

725

750750

Packet Tx

Network Statistics " Tx & Fail"

1 2 3 4 5 6 7 8 9 10 110

10

20

30

40

50

Time "15 minutes Each Interval")

Fail

Figure 18: Data Packet Transmitted and Failed per time slot for DC high voltage test


number of packets transmitted and the number of packets failed to get ACK are plotted. Figure 18

shows that when voltage level is zero, then less than 10 packets fail in the test in each time

interval. But when DC high voltage is applied and increased step by step the number of packets

failed to get acknowledgement increased up to 32 packets per time slot with an average of about

25 packets per time slot.

32

0

50

100

150

200

250

300

350

400

0,00%

10,00%

20,00%

30,00%

40,00%

50,00%

60,00%

70,00%

80,00%

90,00%

100,00%

12:00 14:24 16:48 19:12 21:36 00:00 02:24 04:48 07:12 09:36

DC

Vo

ltag

e (

kV

)

time

Voltage Vs. Stability & Reliability

Stability

Reliability

Voltage

Figure 19: The voltage vs. stability and Reliability

33

6.1.4 Analysis of AC High Voltage Environment Tests Results

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 161694

95

96

97

98

99

100

% N

etw

ork

Sta

bility

Network Statistics

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 160

0.5

1

1.5

2


Late

ncy in s

econd

Figure 20: Stability and latency graph of AC High voltage test


percentage network stability and latency in seconds are plotted. When AC voltage is increasing

during the test, at one point, the both nodes stop transmission and SmartMesh software shows that

the nodes are lost. When test voltage stopped after a few minutes, then the both nodes

reconnected the WSN and started transmitting. We did not use any reboot command to reboot

nodes or manager and waited until the nodes itself reconnected the WSN. As this test was not

repeated, therefore we cannot say anything about the event which might not be detected by the

mote and what is the probability of such event. In Figure 20a the green line shows the network

stability of the network when voltage level is zero or no voltage. Red line shows the network

stability when AC high voltage is present in setup and increasing steps by step. The graph shows

that the stability is around 99% while the voltage level is zero but as voltage level increases, the

stability reaches value around 95.1 %.

The Latency graph is shown in Figure 20b, the green line shows the average latency of the WSN

when voltage level is zero, which is average 0.7 seconds where as red line, shows the latency

when AC high voltage is present, which increased up to maximum 1.4 seconds.

The average value of network stability is 96.15 % with variance 2.645 during AC high voltage

environment test.

34

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1616650

675

700

725

750750Packet Tx

Network Statistics " Tx & Fail"

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16160

10

20

30

40

50

Time "15 minutes Each Interval"

Fail

Figure 21: Data Packet Transmitted and Failed per time slot for AC high voltage test

In Figure 21 the x-axis shows time t interval, each interval is fifteen minutes. Along y-axis Figure

21a shows the number of packets transmitted and Figure 21b shows the number of packets failed

to get ACK. In Figure 21a we can see that when voltage level is zero, the blue line shows that less

than 10 packets fail to get ACK per time slot. Red line shows the graph when voltage is present in

equipment and increasing step by step, it shows that the number of packets failed to get

acknowledgement is up to 35 packets per time slot with an average of about 25 packets per time

slot. As the number of fails increase the number of transmitted packets also increased. When

nodes reconnect, again number of fails starts decreasing. As explained above, due to re

transmission, the protocol supports the retransmission of packet which fails to get ACK to get

maximum reliability.

35

6.2 Path Statistics

6.2.1 Analysis of Non-Industrial Environment Test Results

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3095

95.5

96

96.5

97

97.5

98

98.5

99

99.5

100

Time "15 minutes Each interval"

% P

ath

Sta

bility

Path Statistics

Figure 22: Path stability for Mode to AP in nonindustrial Environment

In Figure 22 the x-axis shows time t interval, each interval is fifteen minutes, y-axis shows

percentage path stability (Path M13 to M1 as shown in Figure 2). Here path stability is not for the

whole network, just for single path from a node to the access point. The path stability varies from

100% to 98.5% in non industrial environments for node to access point path.

36

6.2.2 Analysis Industrial Machines Lab environment Test Results

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2685

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100100


% P

ath S

tability

Path Statistics

Figure 23: Path stability for a mode to AP in machine lab test

In Figure 23, the x-axis shows time t interval, each interval is fifteen minutes (Path M20 to M1 as

shown in Figure 4). In Figure 23 the path stability of the WSN field devices before the machines

were running is more than 99% whereas when the machines were running the path stability

decreases up 89%. The decrease in path stability up to 10% shows that some factor in

environments creates disturbance in WSN.

37

6.2.3 Analysis DC High Voltage Environment Test Result

1 2 3 4 5 6 7 8 9 10 1185

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100


% P

ath

Sta

bility

Path Statistics

Figure 24: Path stability for a mode to AP in DC High voltage test


percentage path stability (Path M13 to M1 as shown in Figure 5). In Figure 24 the path stability

of the WSN field devices is around 99% when voltage level is zero. When the DC high voltage is

present and increasing the path stability decreases up to 89%. The decrease in path stability up to

10% shows that some factor in environments creates disturbance in WSN.

38

6.2.4 Analysis of AC High Voltage Environment Test Results

1 2 3 4 5 6 7 8 9 10 11 12 13 1480

82

84

86

88

90

92

94

96

98

100100


% P

ath S

tability

Path Statistics

Figure 25: Path stability for a mode to AP in AC high Voltage Test


percentage path stability (path between M20 and M1 as shown in Figure 10). In Figure 25 we can

see that the path stability of the WSN field devices during AC high voltage test is dropped up to

86% with an average of 90%.

The red line corresponds to a case when WSN is operating under AC high voltage and gap is

when devices lost connection or signalling due some unknown effect which we mention in

previous section for a case when discharge produced lot of lighting and which can may be due to

increased temperature.

39

6.3 Average RSSI value for Transmission

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30-65

-64

-63

-62

-61

-60

-59

-58

-57

-56

-55

-54

-53

-52

-51

-50

Time "15 minutes Each interval"

A->

B &

B->

A P

ower-dBm

Path Statistics "Average RSSI values for Transmissions

A->B Power

B->A Power

Figure 26: Average value of output power per time slot for transmission in non industrial test

In Figure 26 the x-axis shows time t interval, each interval is fifteen minutes, y-axis shows power

is in dBm. In Figure 26 we can see that in nonindustrial environment tests the total average RSSI

values of transmission about -57.3 dBm.

40

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1616-65

-64

-63

-62

-61

-60

-59

-58

-57

-56

-55

-54

-53

-52

-51

-50

Time interval(15 minute Each interval)

A->

B &

B->

A P

ower-dBm


Figure 27: Average value of output power for transmission in machine lab test

In Figure 27 the x-axis shows time t interval, each interval is fifteen minutes, y-axis shows power

is in dBm. In Figure 27 we can see that in industrial machines lab environment tests the total

average RSSI values of transmission is -57.5 dBm.

Typical RSSI values for network radio strength paths within these distances, indoors in a free-of-

disturbances environment are up to -50 dBm.

41

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1616-65

-64

-63

-62

-61

-60

-59

-58

-57

-56

-55

-54

-53

-52

-51

-50-50


A->

B &

B->

A P

ower-dBm


Figure 28: Average value of output power for transmission in DC High voltage test

1 2 3 4 5 6 7 8 9 10 11 12 13 14-70

-65

-60

-55

-50

-45


A->

B &

B->

A P

ower-dBm


A->B Power

B->A Power

Figure 29: Average value of output power for transmission in AC High voltage test

42

In Figure 28 and 29 the x-axis shows time t interval, each interval is fifteen minutes, y-axis shows

power is in dBm. In Figure 28 we can see that in DC high voltage test the total average RSSI

values of transmission is about -57.0 dBm.

In Figure 29 we can notice that there is no considerable change in RSSI value of transmission in

high voltage test during the first 15 minutes interval. In 1st time slot its value is around -63 dBm,

and -65 dBm.

Average RSSI value of transmission from node to gate way more affected by increasing distance

then by any other factors or environmental condition.

6.4 Analysis of EMI Test Results

6.4.1 Spectral Measurements for EMI in 2.4 GHz band Frequency

For measurement of interference FSH view software and FSH 6, a remote spectrum analyzer up to

6GHz used. Measurements of interference are taken in machine lab environment for both cases that

are when WSN devices are transmitting and when they are disabled and not in transmitting mode.

Figure 30: The 2.4 GHz Spectrum when machines were in off state

In 1st case we observe some interference in 2.4 GHz frequency band when wireless field devices

are operating in environment, because WSN field devices used in these experiments are operated

in 2.4 GHz frequency band.

In 2nd case, when WSN devices are completely in off state and machines are running in full

intensity and we didn't observe any interference in 2.4 GHz band. However we observed

electromagnetic interference in the kHz level.

43

Figure 31: 2.4 GHz Spectrum when machines are operating

For measuring the frequency range which suffers interference while machines are running, we

use the test setup with remote spectrum analyzer and antenna is placed very near of running

machines and monitor all around the machines. But we did not observe any interference in 2.4

GHz band but we observed electromagnetic frequencies in the kHz level.

44

6.4.2 Measurements of EMI in 2.4 GHz Frequency Spectrum in DC High Voltage

Figure 32: 2.4 GHz spectrum DC high voltages test

There is no interfernce obsevered in 2.4 GHz transmission band in DC high voltage test during

the test when WSN field devices are in off state. In high voltage tests we were expacting that

during sparking and in the precence of high voltage, some high frequencies can possibly

generated, but during experiment we did not observe any interfrence in GHz freqency band.

45

6.5 Result Analysis for Complete Test

In this section we analysed the test results of each scenario.

6.5.1 Non Industrial Environments Test

In the nonindustrial environment test, we can observe that the WSN performance is characterized

by 100% reliability and above 99% network stability with an average RSSI value of transmission

around -57.33 dBm .The numbers of packets that fail to get acknowledgement is less than 10 per

time slot, and the average latency is 0.57 second.

In this test we also observed that the average RSSI value of transmission compare to other WSN

performance parameter like reliability and path stability is affected more by changing the distance

between nodes.

6.5.2 Industrial Machines Lab Environment Test

In the machine lab test, the WSN performance is dropped when the status of machine is ‘on’

in comparison to off state. The network stability drops down by 2%, on average and the latency

increases up to 100 ms. The path stability also drops down 10% and the numbers of packets

failing to get acknowledgement increases up to 30 packets per time slot on average.

There is no interference observed in 2.4 GHz band in the machine lab test. However, we observe

the interferences in frequencies range between 1Hz-100 KHz. Hence we can hypothesize that

WSN performance degradation in industrial machine lab test is due to the effect of low EM

frequencies on hardware devices (nodes).

6.5.2.1 DC High Voltage Environment Test

We can observe the degradation in WSN when DC high voltage is present in comparison to when

the voltage level is zero. The drop in network stability is around 2.5% in average test and latency

increases up to 170 ms. Path stability drops down up to 10% and the number of packets failed to

get acknowledgement increased up to average 25 packets per time slot. However, when

experiment is performed for interference in 2.4 GHz band in DC high voltage test, there is no

interference observed in 2.4 GHz.

From results, we conclude that these DC high voltages affect the WSN performance, but these

kinds of industrial environments produced no interferences in 2.4 GHz transmission band. Hence

we can hypothesize that in DC high voltage test the degradation in WSN performance is due to

low band EM frequencies noise at hardware devices because there is no interference observed in

2.4 GHz transmission band.

6.5.3 AC High Voltage Environment Test

In AC high voltage test we observed the degradation in WSN performance. The drop in network

stability is around 4% in average test and latency increased up to 800ms, which is a really

46

noticeable delay. The path stability drop down 12% and the number of packets failed to get

acknowledgement increased up to 36 packets per time slot.

6.5.4 All Test Result Summary

The stability and latency for all the test scenarios are compared in the Table 3and 4 when the

machine state are off and there is no voltage and second table shows when the machine state is on

and voltage.

Table 3. Comparison of Stability and Latency - OFF

Test Stability Latency

Industrial Machine Lab

Test

99.2% – 99.7% 0.51 s – 0.61s

DC High Voltage Test 98.9% – 99.5% 0.60 s – 0.70 s

AC High Voltage Test 99.0% – 99.5% 0.60 s – 0.50 s

Table 4. Comparison of Stability and Latency- ON

Test Stability Latency

Non Industrial Test 99.9% – 99.5% 0.50 s – 0.60 s

Industrial Machine Lab

Test

96.6% – 99.5% 0.55 s – 0.70 s

DC High Voltage Test 95.5% – 98.9% 0.70 s – 0.85 s

AC High Voltage Test 95.0% – 97.3% 0.80 s – 1.40 s

47

7 CONCLUSIONS AND FUTURE WORK

In this thesis, we investigate the WSN performance in high voltage and harsh industrial

environments. We also measure EM frequencies in high voltage and harsh industrial

environments.

During the tests, we observed that the degradation in WSN performance in high voltage and harsh

industrial environments in comparison to non industrial environments. In a case of machine lab

test, the AC high voltage test and DC high voltage test, the degradation in path stability and

increased in latency, prove overall degradation in WSN performance.

We observe that in high voltage and machine lab tests there is no electromagnetic interference

monitored in 2.4 GHz transmission band. The monitored levels of EM frequencies are less than 1

MHz due to high voltage and harsh industrial environments but these observed frequencies less

than 1MHz creates noise at wireless field devices. As WSN filed devices and processor which are

working at high frequencies are very sensitive therefore some low level frequencies noise can

interfere and can generate some unwanted current or voltage level, which can be one of the

reasons of transmission loss and delay.

We also observe during non-industrial tests that in WSN, the RSSI values of transmission are

affected more by increasing distance between nodes than any other conditions or environment

impacts.

Based on the experimental results, it can be concluded that instead of electromagnetic

interference in the transmission band, the performance of WSN in industrial and high-voltage

environments is degraded by EM frequencies less than one MHz, which is responsible for the

noise and disturbance at hardware devices.

Further research and experiments are required on WSN in high voltage and industrial application

to investigate the low level EM frequencies impact on high frequency processors and memory

buffers of wireless devices, as during the tests we observe that wireless filed devises working

under low EM frequencies, sometime generate the buffer full alert.

Nodes and filed devices should be cared for these unintentional EM frequencies during devices

immunity tests and EMC tests. Furthermore, it needs to be work more sensitively for field devices

on electromagnetic compatibility problems from these unintentional EM frequencies.

48

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2007, no. 1, p. 081864, Mar. 2007.

[25] Electromagnetic Interference Involving Fluorescent Lighting Systems, March 1995, available at

http://www.lrc.rpi.edu/programs/NLPIP/lightinganswers/pdf/view/LAEMI.pdf

[26] Norsok Standard: Electrical Systems, Edition 5 July 2007, available at

http://www.standard.no/pagefiles/1262/e-001de5_bjy_070706.pdf

[27] N. M. Boers, I. Nikolaidis, and P. Gburzynski. “Impulsive Interference Avoidance in Dense Wireless

Sensor Networks.” In AdHocNow 2012: Proceedings of the 11th International Conference on Ad-Hoc

Networks and Wireless. Belgrade, Serbia, July 2012.

[28] Panicker, P.K., Satyanand, U.S., Lu, F.K., Emanuel, G., and Svihel, B.T., “Development of Corona

Discharge Apparatus for Supersonic Flow,” AIAA Paper 2003-6925, 2003.

50

9 APPENDIX

D2510 Datasheet [4]

Parameter Min type Max Units Comments

NORMAL OPERATING CONDITIONS

Operational supply

Voltage range

(between Vcc and

GND)

4.0 5.0 5.0 V Including noise and load

regulation

Peak current

210

mA

3V3 out = 0 mA

Average current 100 140 mA +5V_IN at 5.0 V, 25 °C,

+3V3 out = 0 mA

Operating

temperature range -40 85 °C

Antenna Specifications

Frequency range 2.4 2.4835 GHz

Impedance 50 Ω

Gain +2 dBi

Pattern Omni-

directional

DETAILED RADIO SPECIFICATIONS

Operating frequency 2.4000 2.4835 GHz

Number of channels 15

Channel separation 5 MHz

Occupied channel 2.7 MHz At -20 dBc

bandwidth

Modulation

IEEE 802.15.4 direct

sequence spread

spectrum (DSSS)

Raw data rate 250 kbps

Receiver sensitivity -90 dBm At 1% PER, , 25° C

Output power, EIRP -2 dBm Vcc = 3 V, 25° C +2 dBi

antenna

Range* Indoor-

outdoor

25

200

m

m

25° C, 50% RH, 1 meter

above ground, +2 dBi

Omni-directional antenna

* values when power amplifier disable

51

SMARTMESH IA-510 M2510 [4]

WIRELESS SENSOR NETWORK PERFORMANCE IN HIGH …

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